Effects of weak input side mode suppression ratio and output filtration on the intensity noise of a self-seeded gain switched optical pulses at 2.5 GHz

Mode partition noise is shown to be a cause for concern in terms of the intensity noise induced on a self-seeded gain-switched pulse when filtering is used to increase the side mode suppression ratio (SMSR) of the output signal to >30 dB. The inherent SMSR of a self-seeded gain switched pulse is revealed to be a vital parameter especially when output filtration is used. Our results portray the fact that such a procedure would lead to an introduction of noise on the SSGS pulses if the inherent SMSR is weak, and may ultimately determine whether or not a source is suitable for use in WDM or OTDM optical communication networks

Correlates of Participation in Neighborhood Organizations

Also PCMA Working Paper #32.http://deepblue.lib.umich.edu/bitstream/2027.42/51228/1/462.pd

Near-Field Microwave Microscopy on nanometer length scales

The Near-Field Microwave Microscope (NSMM) can be used to measure ohmic losses of metallic thin films. We report on the presence of a new length scale in the probe-to- sample interaction for the NSMM. We observe that this length scale plays an important role when the tip to sample separation is less than about 10nm. Its origin can be modeled as a tiny protrusion at the end of the tip. The protrusion causes deviation from a logarithmic increase of capacitance versus decreasing height of the probe above the sample. We model this protrusion as a cone at the end of a sphere above an infinite plane. By fitting the frequency shift of the resonator versus height data (which is directly related to capacitance versus height) for our experimental setup, we find the protrusion size to be 3nm to 5nm. For one particular tip, the frequency shift of the NSMM relative to 2 micrometers away saturates at a value of about -1150 kHz at a height of 1nm above the sample, where the nominal range of sheet resistance values of the sample are 15 ohms to 150 ohms. Without the protrusion, the frequency shift would have followed the logarithmic dependence and reached a value of about -1500 kHz.Comment: 6 pages, 7 figures (included in 6 pages

Source attribution of ozone in Southeast Texas before and after the Deepwater Horizon accident using satellite, sonde, surface monitor, and air mass trajectory data

Since the summer of 2004, over 300 ozonesondes have been launched from Rice University (29.7 N, 95.4 W) or the University of Houston (29.7 N, 95.3 W), each \u3c 5 km from downtown Houston. The Texas Commission on Environmental Quality maintains a large database of hourly surface ozone observations in Southeast Texas. In this study, we identify the contributions to surface ozone pollution levels from natural and anthropogenic sources, both local and remote in nature. This source identification is performed two ways: 1) through an analysis of sonde data, including ozone concentrations, wind speed and direction, and relative humidity data, and 2) through an analysis that combines trajectory calculations with surface monitor data. We also examine regional changes in Ozone Monitoring Instrument (OMI) measurements of formaldehyde and ozone from 2004 – 2010. In particular, we compare the 2010 sonde, surface monitor, and satellite data after the Deepwater Horizon accident with data from previous years to determine the impact, if any, of the large source of hydrocarbons in the Gulf of Mexico on air quality in Southeast Texas

Power efficient job scheduling by predicting the impact of processor manufacturing variability

Modern CPUs suffer from performance and power consumption variability due to the manufacturing process. As a result, systems that do not consider such variability caused by manufacturing issues lead to performance degradations and wasted power. In order to avoid such negative impact, users and system administrators must actively counteract any manufacturing variability. In this work we show that parallel systems benefit from taking into account the consequences of manufacturing variability when making scheduling decisions at the job scheduler level. We also show that it is possible to predict the impact of this variability on specific applications by using variability-aware power prediction models. Based on these power models, we propose two job scheduling policies that consider the effects of manufacturing variability for each application and that ensure that power consumption stays under a system-wide power budget. We evaluate our policies under different power budgets and traffic scenarios, consisting of both single- and multi-node parallel applications, utilizing up to 4096 cores in total. We demonstrate that they decrease job turnaround time, compared to contemporary scheduling policies used on production clusters, up to 31% while saving up to 5.5% energy.Postprint (author's final draft

The Federal Reserve, the Bank of England, and the Rise of the Dollar as an International Currency, 1914-1939

This paper provides new evidence on the rise of the dollar as an international currency, focusing on its role in the conduct of trade and the provision of trade credit. We show that the shift to the dollar occurred much earlier than conventionally supposed: during and immediately after World War I. Not just market forces but also policy support – the Fed in its role as market maker – was important for the dollar’s overtaking of sterling as the leading international currency. On balance, this experience challenges the popular notion of international currency status as being determined mainly by market size. It suggests that the popular image of strongly increasing returns and pervasive network externalities leaving room for only one monetary technology is misleading.international currency, trade credit, network externalities

The Rise and Fall of the Dollar, or When Did the Dollar Replace Sterling as the Leading International Currency?

We present new evidence on the currency composition of foreign exchange reserves in the 1920s and 1930s. Contrary to the presumption that the pound sterling continued to dominate the U.S. dollar in central bank reserves until after World War II, we show that the dollar first overtook sterling in the mid-1920s. This suggests that the network effects thought to lend inertia to international currency status and to create incumbency advantages for the dominant international currency do not apply in the reserve currency domain. Our new evidence is similarly incompatible with the notion that there is only room in the market for one dominant reserve currency at a point in time. Our findings have important implications for our understanding of interwar monetary history but also for the prospects of the dollar and the euro as reserve currencies.

Kolyvagin systems of Stark units

In this paper we construct, using Stark elements of Rubin [Ann. Inst. Fourier (Grenoble) 46 (1996), no. 1, 33-62], Kolyvagin systems for certain modified Selmer structures (that are adjusted to have core rank one in the sense of [Mem. Amer. Math. Soc. 168 (2004), no. 799] and prove a Gras-type conjecture, relating these Kolyvagin systems to appropriate ideal class groups, refining the results of Rubin [J. Reine Angew. Math. 425 (1992), 141-154].Comment: 27 pages, revised version, accepted for publication in J. Reine Angew. Math. (Crelle's